/* ========================================
   CSS Variables (Design System)
   ======================================== */
:root {
  --color-aws-dark: #232F3E;
  --color-aws-orange: #dc7600;
  --color-aws-orange-original: #FF9900;
  --color-aws-orange-hover: #EC7211;
  --color-text-primary: #374151;
  --color-text-secondary: #6B7280;
  --color-text-tertiary: #6f7682;
  --color-text-white: #FFFFFF;
  --color-bg-light: #F9FAFB;
  --color-bg-white: #FFFFFF;
  --color-bg-dark: #1F2937;
  --color-bg-gradient-start: #232F3E;
  --color-bg-gradient-end: #374151;
  --color-border: #909296;
  --color-border-light: #E5E7EB;
  --color-shadow: rgba(0, 0, 0, 0.1);
  --color-success: #10B981;
  --color-warning: #F59E0B;
  --color-error: #EF4444;
  --color-info: #3B82F6;
  --spacing-xs: 5px;
  --spacing-sm: 10px;
  --spacing-md: 15px;
  --spacing-base: 20px;
  --spacing-lg: 25px;
  --spacing-xl: 30px;
  --spacing-2xl: 40px;
  --spacing-3xl: 60px;
  --spacing-4xl: 80px;
  --font-size-xs: 0.75em;
  --font-size-sm: 0.85em;
  --font-size-base: 0.95em;
  --font-size-md: 1em;
  --font-size-lg: 1.2em;
  --font-size-xl: 1.5em;
  --font-size-2xl: 2em;
  --font-size-3xl: 2.5em;
  --font-weight-normal: 400;
  --font-weight-medium: 500;
  --font-weight-semibold: 600;
  --font-weight-bold: 700;
  --line-height-tight: 1.25;
  --line-height-normal: 1.5;
  --line-height-relaxed: 1.75;
  --radius-sm: 6px;
  --radius-md: 8px;
  --radius-base: 10px;
  --radius-lg: 15px;
  --radius-xl: 20px;
  --radius-full: 50%;
  --shadow-xs: 0 1px 2px rgba(0, 0, 0, 0.05);
  --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.1);
  --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 10px 40px rgba(0, 0, 0, 0.2);
  --shadow-xl: 0 20px 50px rgba(0, 0, 0, 0.3);
  --shadow-focus: 0 0 0 3px rgba(255, 153, 0, 0.3);
  --shadow-orange: 0 4px 12px rgba(255, 153, 0, 0.4);
  --shadow-orange-hover: 0 6px 20px rgba(255, 153, 0, 0.6);
  --header-height: 60px;
  --container-max-width: 1200px;
  --transition-fast: 0.15s ease;
  --transition-base: 0.3s ease;
  --transition-slow: 0.5s ease;
  --z-base: 1;
  --z-sticky: 500;
  --z-scroll-top: 1000;
  --z-progress-bar: 1001;
  --z-header: 1002;
}

/* ========================================
   Container
   ======================================== */
.container {
  max-width: var(--container-max-width);
  margin: 0 auto; padding: var(--spacing-2xl);
  background: var(--color-bg-white);
  border-radius: 16px;
  box-shadow: var(--shadow-lg);
}

/* ========================================
   Hero Section
   ======================================== */
.hero {
  background: linear-gradient(135deg, #232F3E 0%, #37475A 50%, #485769 100%);
  border-radius: var(--radius-xl);
  padding: var(--spacing-3xl) var(--spacing-2xl);
  margin-bottom: var(--spacing-2xl);
  text-align: center;
  position: relative;
  overflow: hidden;
}
.hero::before {
  content: ''; position: absolute; top: -50%; left: -50%;
  width: 200%; height: 200%;
  background: radial-gradient(circle at 30% 70%, rgba(255,153,0,0.08) 0%, transparent 50%),
              radial-gradient(circle at 70% 30%, rgba(59,130,246,0.06) 0%, transparent 50%);
  animation: heroGlow 8s ease-in-out infinite alternate;
}
@keyframes heroGlow {
  0% { transform: translate(0,0); }
  100% { transform: translate(2%,1%); }
}
.hero-badge {
  display: inline-block; background: rgba(255,153,0,0.2);
  color: var(--color-aws-orange-original); padding: 8px 20px;
  border-radius: 30px; font-size: 20px; font-weight: var(--font-weight-semibold);
  margin-bottom: var(--spacing-base); position: relative;
  border: 1px solid rgba(255,153,0,0.3);
}
.hero h1 {
  font-size: 2.2em; color: var(--color-text-white);
  margin-bottom: var(--spacing-base); position: relative;
  line-height: var(--line-height-tight);
}
.hero-sub {
  font-size: 1.1em; color: rgba(255,255,255,0.8);
  max-width: 700px; margin: 0 auto; position: relative;
  line-height: var(--line-height-relaxed);
}

/* ========================================
   Key Takeaways
   ======================================== */
.key-takeaways {
  background: linear-gradient(135deg, #FFF7ED 0%, #FFFBEB 100%);
  border: 2px solid #FDBA74; border-radius: var(--radius-lg);
  padding: var(--spacing-xl); margin-bottom: var(--spacing-2xl);
}
.key-takeaways h2 {
  font-size: 1.4em; color: var(--color-aws-dark);
  margin-bottom: var(--spacing-base); display: flex; align-items: center; gap: 10px;
  border-bottom: none; padding-bottom: 0;
}
.takeaway-grid {
  display: grid; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); gap: var(--spacing-base);
}
.takeaway-card {
  background: var(--color-bg-white); border-radius: var(--radius-base);
  padding: var(--spacing-base); border-left: 4px solid var(--color-aws-orange);
  box-shadow: var(--shadow-xs);
}
.takeaway-card .num {
  display: inline-flex; align-items: center; justify-content: center;
  width: 32px; height: 32px; border-radius: var(--radius-full);
  background: var(--color-aws-orange); color: white;
  font-weight: var(--font-weight-bold); font-size: 20px;
  margin-bottom: 8px;
}
.takeaway-card h3 {
  font-size: 1.05em; color: var(--color-aws-dark); margin-bottom: 6px;
}
.takeaway-card p { font-size: 20px; color: var(--color-text-secondary); }

/* ========================================
   Section Styles
   ======================================== */
.section {
  margin-bottom: var(--spacing-2xl);
  background: var(--color-bg-light);
  padding: var(--spacing-xl);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
}
.section-title {
  font-size: 1.5em; color: var(--color-aws-dark);
  margin-bottom: var(--spacing-base);
  padding-bottom: var(--spacing-sm);
  border-bottom: 3px solid var(--color-aws-orange);
  display: flex; align-items: center; gap: 10px;
}
.section-subtitle {
  font-size: 1.15em; color: var(--color-aws-dark);
  margin: var(--spacing-base) 0 var(--spacing-sm) 0;
  padding-left: 12px; border-left: 4px solid var(--color-info);
}
.section p, .section li {
  font-size: 20px; line-height: var(--line-height-relaxed);
  color: var(--color-text-primary);
}
.section ul { padding-left: 1.5em; margin: var(--spacing-sm) 0; }
.section li { margin-bottom: 6px; }

/* ========================================
   Analogy Table
   ======================================== */
.analogy-table-wrap {
  overflow-x: auto; margin: var(--spacing-base) 0;
}
.analogy-table {
  width: 100%; border-collapse: collapse;
  border-radius: var(--radius-base); overflow: hidden;
  box-shadow: var(--shadow-sm);
}
.analogy-table th {
  background: var(--color-aws-dark); color: var(--color-text-white);
  padding: 14px 18px; font-size: 20px; text-align: left;
  font-weight: var(--font-weight-semibold);
}
.analogy-table td {
  padding: 14px 18px; font-size: 20px;
  border-bottom: 1px solid var(--color-border-light);
  background: var(--color-bg-white);
}
.analogy-table tr:last-child td { border-bottom: none; }
.analogy-table tr:hover td { background: #FFF7ED; }

/* ========================================
   Cards Grid
   ======================================== */
.cards-grid {
  display: grid; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); gap: var(--spacing-base);
}
.card {
  background: var(--color-bg-white); border-radius: var(--radius-lg);
  padding: var(--spacing-base); box-shadow: var(--shadow-sm);
  border: 1px solid var(--color-border-light);
  transition: all var(--transition-base);
}
.card:hover { transform: translateY(-3px); box-shadow: var(--shadow-md); }
.card-icon {
  font-size: 2em; margin-bottom: var(--spacing-sm);
}
.card h3 { font-size: 1.1em; margin-bottom: 8px; color: var(--color-aws-dark); }
.card p { font-size: 20px; color: var(--color-text-secondary); }

/* ========================================
   SVG Diagram Container
   ======================================== */
.diagram-container {
  margin: var(--spacing-base) 0;
  background: var(--color-bg-white);
  border-radius: var(--radius-lg);
  padding: var(--spacing-base);
  box-shadow: var(--shadow-sm);
  border: 1px solid var(--color-border-light);
  overflow-x: auto;
}
.diagram-container svg {
  width: 100%; height: auto; display: block;
}
.diagram-caption {
  text-align: center; font-size: 20px; color: var(--color-text-secondary);
  margin-top: var(--spacing-sm); font-weight: var(--font-weight-medium);
}

/* ========================================
   Comparison (Best vs Anti)
   ======================================== */
.comparison-grid {
  display: grid; grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); gap: var(--spacing-base);
}
.best-card {
  background: #ECFDF5; border: 2px solid #34D399; border-radius: var(--radius-lg);
  padding: var(--spacing-base);
}
.best-card h3 { color: #065F46; margin-bottom: var(--spacing-sm); font-size: 1.1em; }
.best-card li { font-size: 20px; color: #065F46; margin-bottom: 6px; }
.anti-card {
  background: #FEF2F2; border: 2px solid #F87171; border-radius: var(--radius-lg);
  padding: var(--spacing-base);
}
.anti-card h3 { color: #991B1B; margin-bottom: var(--spacing-sm); font-size: 1.1em; }
.anti-card li { font-size: 20px; color: #991B1B; margin-bottom: 6px; }

/* ========================================
   Tabbed Code Examples
   ======================================== */
.code-tabs {
  margin: var(--spacing-base) 0;
  border-radius: var(--radius-lg); overflow: hidden;
  box-shadow: var(--shadow-sm);
}
.tab-buttons {
  display: flex; background: var(--color-aws-dark);
}
.tab-btn {
  padding: 12px 20px; border: none; background: transparent;
  color: rgba(255,255,255,0.6); cursor: pointer; font-size: 20px;
  font-weight: var(--font-weight-medium); transition: all var(--transition-base);
  border-bottom: 3px solid transparent;
}
.tab-btn.active {
  color: var(--color-aws-orange-original);
  border-bottom-color: var(--color-aws-orange-original);
  background: rgba(255,153,0,0.1);
}
.tab-btn:hover { color: var(--color-text-white); }
.tab-content {
  display: none; background: #1a1a2e; padding: var(--spacing-base);
}
.tab-content.active { display: block; }
.tab-content pre {
  color: #E5E7EB; font-family: 'Courier New', monospace;
  font-size: 18px; line-height: 1.6; overflow-x: auto;
  white-space: pre-wrap; word-break: break-all;
}
.tab-content .comment { color: #6B7280; }
.tab-content .key { color: #93C5FD; }
.tab-content .value { color: #86EFAC; }
.tab-content .cmd { color: #FDBA74; }

/* ========================================
   Troubleshooting
   ======================================== */
.trouble-card {
  background: var(--color-bg-white); border-radius: var(--radius-lg);
  padding: var(--spacing-base); margin-bottom: var(--spacing-base);
  border-left: 4px solid var(--color-error);
  box-shadow: var(--shadow-xs);
}
.trouble-card h3 {
  font-size: 1.05em; color: var(--color-error); margin-bottom: 8px;
  display: flex; align-items: center; gap: 8px;
}
.trouble-card .cause {
  font-size: 20px; color: var(--color-text-secondary); margin-bottom: 8px;
}
.trouble-card .solution {
  font-size: 20px; color: var(--color-success); font-weight: var(--font-weight-medium);
}

/* ========================================
   Exam Tips
   ======================================== */
.exam-tips {
  background: linear-gradient(135deg, #EEF2FF 0%, #E0E7FF 100%);
  border: 2px solid #818CF8; border-radius: var(--radius-lg);
  padding: var(--spacing-xl); margin-bottom: var(--spacing-2xl);
}
.exam-tips h2 {
  font-size: 1.4em; color: #312E81; margin-bottom: var(--spacing-base);
  display: flex; align-items: center; gap: 10px;
  border-bottom: none; padding-bottom: 0;
}
.exam-tip-item {
  background: var(--color-bg-white); border-radius: var(--radius-base);
  padding: var(--spacing-base); margin-bottom: var(--spacing-sm);
  border-left: 4px solid #818CF8;
}
.exam-tip-item h3 {
  font-size: 1em; color: #4338CA; margin-bottom: 6px;
}
.exam-tip-item p { font-size: 20px; color: var(--color-text-primary); }

/* ========================================
   FAQ Accordion
   ======================================== */
.faq-item {
  background: var(--color-bg-white); border-radius: var(--radius-base);
  margin-bottom: var(--spacing-sm); box-shadow: var(--shadow-xs);
  border: 1px solid var(--color-border-light); overflow: hidden;
}
.faq-question {
  width: 100%; padding: var(--spacing-base) var(--spacing-base);
  border: none; background: transparent; cursor: pointer;
  display: flex; justify-content: space-between; align-items: center;
  font-size: 20px; font-weight: var(--font-weight-semibold);
  color: var(--color-text-primary); text-align: left;
}
.faq-question:hover { background: var(--color-bg-light); }
.faq-arrow {
  transition: transform var(--transition-base);
  font-size: 20px; color: var(--color-aws-orange);
}
.faq-item.open .faq-arrow { transform: rotate(180deg); }
.faq-answer {
  max-height: 0; overflow: hidden;
  transition: max-height 0.4s ease, padding 0.3s ease;
  padding: 0 var(--spacing-base);
}
.faq-item.open .faq-answer {
  max-height: 600px;
  padding: 0 var(--spacing-base) var(--spacing-base) var(--spacing-base);
}
.faq-answer p { font-size: 20px; color: var(--color-text-secondary); line-height: var(--line-height-relaxed); }

/* ========================================
   Cheat Sheet
   ======================================== */
.cheat-sheet {
  background: linear-gradient(135deg, #F0FDF4 0%, #ECFDF5 100%);
  border: 2px solid #34D399; border-radius: var(--radius-lg);
  padding: var(--spacing-xl); margin-bottom: var(--spacing-base);
}
.cheat-sheet h2 {
  font-size: 1.4em; color: #065F46;
  display: flex; align-items: center; gap: 10px;
  border-bottom: none; padding-bottom: 0;
  margin-bottom: var(--spacing-base);
}
.cheat-grid {
  display: grid; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); gap: var(--spacing-base);
}
.cheat-item {
  background: var(--color-bg-white); border-radius: var(--radius-base);
  padding: var(--spacing-base); border: 1px solid #A7F3D0;
}
.cheat-item h3 {
  font-size: 1em; color: #065F46; margin-bottom: 6px;
  display: flex; align-items: center; gap: 6px;
}
.cheat-item p { font-size: 20px; color: var(--color-text-secondary); }
.cheat-item code {
  background: #D1FAE5; padding: 2px 8px; border-radius: 4px;
  font-size: 18px; color: #065F46; font-family: monospace;
}

/* ========================================
   Highlight Box
   ======================================== */
.highlight-box {
  background: #FFFBEB; border: 1px solid #FCD34D;
  border-radius: var(--radius-base); padding: var(--spacing-base);
  margin: var(--spacing-base) 0;
}
.highlight-box p { font-size: 20px; color: #92400E; }

.info-box {
  background: #EFF6FF; border: 1px solid #93C5FD;
  border-radius: var(--radius-base); padding: var(--spacing-base);
  margin: var(--spacing-base) 0;
}
.info-box p { font-size: 20px; color: #1E40AF; }

/* ========================================
   Glossary
   ======================================== */
.glossary-grid {
  display: grid; grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); gap: var(--spacing-sm);
}
.glossary-item {
  background: var(--color-bg-white); border-radius: var(--radius-sm);
  padding: 14px; border: 1px solid var(--color-border-light);
}
.glossary-item dt {
  font-weight: var(--font-weight-bold); color: var(--color-aws-dark);
  font-size: 20px; margin-bottom: 4px;
}
.glossary-item dd { font-size: 20px; color: var(--color-text-secondary); margin: 0; }

/* ========================================
   ToC (Table of Contents)
   ======================================== */
.toc {
  background: var(--color-bg-white); border: 2px solid var(--color-border-light);
  border-radius: var(--radius-lg); padding: var(--spacing-xl);
  margin-bottom: var(--spacing-2xl);
}
.toc h2 {
  font-size: 1.3em; margin-bottom: var(--spacing-base);
  border-bottom: 2px solid var(--color-aws-orange);
  padding-bottom: 8px; color: var(--color-aws-dark);
}
.toc ol {
  padding-left: 1.5em; counter-reset: toc-counter;
  list-style: none;
}
.toc li {
  counter-increment: toc-counter;
  margin-bottom: 8px; font-size: 20px;
}
.toc li::before {
  content: counter(toc-counter) ". ";
  color: var(--color-aws-orange); font-weight: var(--font-weight-bold);
}
.toc a {
  color: var(--color-text-primary); text-decoration: none;
  transition: color var(--transition-base);
}
.toc a:hover { color: var(--color-aws-orange); }

/* ========================================
   Step Flow
   ======================================== */
.step-flow {
  display: flex; flex-direction: column; gap: var(--spacing-base);
}
.step-item {
  display: flex; gap: var(--spacing-base); align-items: flex-start;
}
.step-num {
  flex-shrink: 0; width: 48px; height: 48px;
  background: var(--color-aws-dark); color: white;
  border-radius: var(--radius-full); font-size: 22px;
  font-weight: var(--font-weight-bold);
  display: flex; align-items: center; justify-content: center;
}
.step-body {
  flex: 1; background: var(--color-bg-white);
  border-radius: var(--radius-base); padding: var(--spacing-base);
  border: 1px solid var(--color-border-light);
}
.step-body h3 { font-size: 1.05em; color: var(--color-aws-dark); margin-bottom: 6px; }
.step-body p { font-size: 20px; color: var(--color-text-secondary); }
.step-body code {
  background: #F3F4F6; padding: 2px 8px; border-radius: 4px;
  font-size: 18px; font-family: monospace; color: var(--color-aws-dark);
}

/* ========================================
   Scroll-to-top
   ======================================== */
.scroll-to-top {
  position: fixed; bottom: 25px; right: 25px;
  width: 50px; height: 50px;
  background: linear-gradient(135deg, var(--color-aws-orange-original), var(--color-aws-orange-hover));
  color: white; border: none; border-radius: var(--radius-full);
  font-size: 1.5em; cursor: pointer;
  box-shadow: var(--shadow-orange);
  opacity: 0; visibility: hidden;
  transition: all var(--transition-base);
  z-index: var(--z-scroll-top);
  display: flex; align-items: center; justify-content: center;
}
.scroll-to-top.show { opacity: 1; visibility: visible; }
.scroll-to-top:hover { transform: translateY(-5px); box-shadow: var(--shadow-orange-hover); }

/* ========================================
   Responsive
   ======================================== */
@media (max-width: 768px) {
  body { font-size: 18px; }
  .container { padding: var(--spacing-base); margin: var(--spacing-sm); }
  .hero { padding: var(--spacing-2xl) var(--spacing-base); }
  .hero h1 { font-size: 1.6em; }
  .cards-grid, .takeaway-grid, .comparison-grid, .cheat-grid, .glossary-grid {
    grid-template-columns: 1fr;
  }
  .tab-buttons { flex-wrap: wrap; }
  .step-item { flex-direction: column; align-items: center; text-align: center; }
}

/* ========================================
   Accessibility
   ======================================== */
a:focus, button:focus { outline: 3px solid var(--color-aws-orange-original); outline-offset: 2px; }
.skip-link {
  position: absolute; top: -40px; left: 0;
  background: var(--color-aws-orange); color: white;
  padding: 8px 16px; text-decoration: none; z-index: 9999;
  border-radius: 0 0 4px 0; font-weight: var(--font-weight-bold);
}
.skip-link:focus { top: 0; }